EP0406823B1 - Milieux d'enregistrement magnéto-optique - Google Patents

Milieux d'enregistrement magnéto-optique Download PDF

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Publication number
EP0406823B1
EP0406823B1 EP90112759A EP90112759A EP0406823B1 EP 0406823 B1 EP0406823 B1 EP 0406823B1 EP 90112759 A EP90112759 A EP 90112759A EP 90112759 A EP90112759 A EP 90112759A EP 0406823 B1 EP0406823 B1 EP 0406823B1
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Prior art keywords
film
magnetooptical recording
recording medium
atom
magnetooptical
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German (de)
English (en)
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EP0406823A3 (en
EP0406823A2 (fr
Inventor
Kiyotaka c/o Mitsui Petrochem. Ind.Ltd. Shindo
Hidehiko c/o Mitsui Petrochem.Ind.Ltd. Hashimoto
Kunihiko c/o Mitsui Petrochem.Ind.Ltd. Mizumoto
Masayoshi c/o Mitsui Petrochem.Ind.Ltd. Kurisu
Akira c/o Mitsui Petrochem. Ind.Ltd. Todo
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Mitsui Petrochemical Industries Ltd
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Mitsui Petrochemical Industries Ltd
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
    • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
    • G11B7/253—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of substrates
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
    • G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
    • G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
    • G11B11/10582—Record carriers characterised by the selection of the material or by the structure or form
    • G11B11/10584—Record carriers characterised by the selection of the material or by the structure or form characterised by the form, e.g. comprising mechanical protection elements

Definitions

  • This invention relates to magnetooptical recording media with excellent oxidation resistance and magnetooptical recording characteristics, and more particularly to magnetooptical recording media with excellent oxidation resistance and also with such excellent magnetooptical recording characteristics as broad recording power margin, small dependence on linear velocity of recording sensitivity and high C/N ratio and, moreover, with excellent adhesion between a substrate and a protective film.
  • magnetooptical recording films composed of alloys comprising transition metals, such as iron and cobalt, and rare earth elements, such as terbium (Tb) and gadolinium (Gd), have a magnetic easy axis perpendicular to the film and are capable of forming a small reversed magnetic domain with magnetization anti-parallel to the magnetization of the film.
  • Tb transition metal
  • Gd gadolinium
  • Tb-Fe magnetooptical recording films containing 15-30 atom% of Tb.
  • magnetooptical recording films of Tb-Fe system to which a third metal component has been added.
  • magnetooptical recording films of Tb-Co or Tb-Fe-Co system are also known.
  • Magnetooptical recording media having a substrate and thereon such magnetooptical recording films as mentioned above are generally lacking in oxidation resistance, and they have been required also to have improved recording sensitivity.
  • the expression that the recording power margin is broad at the time of writing information in the magnetooptical recording medium by the use as a writing ray of light of a laser beam or the like is intended to mean that the information can be written accurately in the medium even when a power of the laser beam used varies more or less
  • the dependence on linear velocity of recording sensitivity is intended to mean that at the time of writing information in the medium by the use as a writing ray of light of a laser beam of the like, variation in the optimum recording power of the laser beam is small even when the rotational speed of the portion of the medium in which the information is written varies.
  • magnetooptical recording media having a substrate and a magnetooptical recording film interposed between the substrate and a protective film, it is desired that adhesion between the substrate and the protective film is excellent.
  • magnetooptical recording media as having excellent oxidation resistance, high C/N ratio, broad recording power margin, small dependence on linear velocity of recording sensitivity and excellent adhesion between the substrate and protective film will make their appearance.
  • the present invention is intended to solve such problems associated with the prior art as mentioned above, and an object of the invention is to provide such magnetooptical recording media as having excellent oxidation resistance without deterioration in magnetooptical recording characteristics even when used for a long period of time, high C/N ratio, broad recording power margin, small dependence on linear velocity of recording sensitivity and excellent adhesion between the substrate and the protective film.
  • the magnetooptical recording medium of the present invention having a first protective film (layer) [a first enhancing film (layer)], a magnetooptical recording film (layer), a second protective film (layer) [a second enhancing film (layer)] and a metallic film (layer) formed on a substrate in that order is characterized in that:
  • the substrate is composed of a cycloolefin random copolymer of ethylene and at least one of cycloolefins represented by the formula [I] or [II], said copolymer desirably having an intrinsic viscosity of 0.05-10 dl/g.
  • n is 0 (zero) or 1
  • m is 0 (zero) or a positive integer
  • R 1 - R 18 are individually hydrogen, halogen or hydrocarbon group
  • R 15 - R 18 may, linking together, form a mono- or polycyclic ring which may have a double bond
  • R 15 together with R 16 or R 17 together with R 18 may form an alkylidene group.
  • R 1 is 0 (zero) or an integer of at least 1, m and n are each 0 (zero), 1 or 2, R 1 -R 15 is individually hydrogen, halogen, aliphatic hydrocarbon group, aromatic hydrocarbon group or alkoxy group, and R 5 (or R 6 ) and R 9 (or R 7 ) may be linked together through an alkylene group of 1-3 carbon atoms or linked together directly without through the alkylene group.
  • a double-sided magnetooptical recording medium which is obtained by joining a first magnetooptical recording medium having the above-mentioned first protective film, the magnetooptical recording film, the second protective film and the metallic film formed on the substrate in that order to a second magnetooptical recording medium of the same structure as in the first magnetooptical recording medium so that the metallic film of the first magnetooptical recording medium and the metallic film of the second magnetooptical recording medium are positioned face to face through an adhesive layer.
  • the magnetooptical recording media of the present invention are excellent in oxidation resistance, free from deterioration of recording characteristics even when used for a long period of time, and high in C/N ratio, broad in recording power margin, small in dependence on linear velocity of recording sensitivity and also excellent in adhesion between the substrate and the first protective film.
  • Fig. 1 is a rough sectional view of the magnetooptical recording medium of the present invention.
  • Fig. 2 is a rough sectional view of the double-sided magnetooptical recording medium of the invention.
  • the magnetooptical recording media of the present invention are illustrated below in detail.
  • Fig. 1 is a rough sectional view of one embodiment of the magnetooptical recording media of the present invention.
  • a first protective film 3, magnetooptical recording film 4, second protective film 5 and metallic film 6 are laminated on a substrate 2 in that order.
  • Materials for the above-mentioned substrate 2 used in the invention are not particularly limited to specific ones. However, when laser beam is incident upon the substrate 2, the materials used therefor are preferably those which are transparent. Besides inorganic materials such as glass, aluminum and the like, such transparent materials include, for example, organic materials such as poly(methyl methacrylate), polycarbonate, polymer alloys of polycarbonate with polystyrene, such cycloolefin random copolymers as disclosed in U.S. Patent No. 4,614,778, such cycloolefin random copolymers (A) as mentioned below, poly4-methyl-1-pentene, epoxy resins, polyether sulfone, polysulfone, polyether imide and the like.
  • organic materials such as poly(methyl methacrylate), polycarbonate, polymer alloys of polycarbonate with polystyrene, such cycloolefin random copolymers as disclosed in U.S. Patent No. 4,614,778, such cycloole
  • poly(methyl methacrylate), polycarbonate such cycloolefin random copolymers as disclosed in U.S. Patent No. 4,614,778 and the cycloolefin random copolymers (A) as mentioned below.
  • particularly desirable materials for the substrate used in the present invention are cycloolefin random copolymers of (a) ethylene and (b) a cycloolefin represented by the following formula [I] or [II], said random copolymer having an intrinsic viscosity [ ⁇ ] of 0.05-10 dl/g as measured in decalin at 135°C.
  • This cycloolefin random copolymer desirably has a softening temperature (TMA) of 70°C and is called hereinafter "the cycloolefin random copolymer [A]".
  • TMA softening temperature
  • m 0 (zero) or a positive integer
  • R 1 - R 18 are individually hydrogen, halogen or hydrocarbon group
  • R 15 - R 18 may, linking together, form a mono- or polycyclic ring which may have a double bond
  • R 15 together with R 16 or R 17 together with R 18 may form an alkylidene group.
  • R 1 -R 15 are individually an atom or group selected from the group consisting of hydrogen, halogen, aliphatic hydrocarbon group, aromatic hydrocarbon and alkoxy, and R 5 (or R 6 ) and R 9 (or R 7 ) may be linked together through an alkylene group of 1-3 carbon atoms or may be linked together directly without through any group.
  • n is 0 (zero) or 1, preferably 0 (zero), and m is 0 (zero) or a positive integer, preferably 0-3.
  • p is 0 (zero) or an integer of at least 1, preferably an integer of 0-3.
  • R 1 -R 18 (formula [I]) or R 1 -R 15 (formula [II]) individually represent an atom or group selected from the group consisting of hydrogen, halogen and hydrocarbon, wherein the halogen includes, for example, fluorine, chlorine, bromine and iodine atoms, and the hydrocarbon group includes usually alkyl of 1-6 carbon atoms and cycloalkyl of 3-6 carbon atoms. Concrete examples of the alkyl include methyl, ethyl, isopropyl, isobutyl and amyl, and those of the cycloalkyl include cyclohexyl, cyclopropyl, cyclobutyl and cyclopentyl.
  • R 5 (or R 6 ) and R 9 (or R 7 ) may be linked together through an alkylene group of 1-3 carbon atoms or may be linked together directly without through any group.
  • R 15 -R 18 may form, linking together (in combination), a mono- or polycyclic ring which may have a double bond, and R 15 together with R 16 , or R 17 together with R 18 may form an alkylidene group.
  • alkylidene group includes usually alkylidene of 2-4 carbon atoms, and concrete examples thereof include ethylidene, propylidene, isopropylidene and isobutylidene.
  • the cycloolefins represented by the above-mentioned formula [I] or [II] may easily be prepared by condensing cyclopentadienes with corresponding olefins or cycloolefins through Diels-Alder reaction.
  • cycloolefins represented by the above-mentioned formula [I] or [II] used in the present invention include concretely:
  • Tetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene derivative including such as those mentioned below.
  • Hexacyclo[6.6.1.1 3,6 .1 10,13 .0 2,7 .0 9,14 ]-4-heptadecene derivative including such as those mentioned below.
  • Pentacyclo[6.6.1.1 3,6 .0 2,7 .0 9,14 ]-4-hexadecene derivative including such as those mentioned below.
  • Heptacyclo-5-eicosene derivative or heptacyclo-5-heneicosene derivative including such as those mentioned below.
  • Tricyclo[4.3.0.1 2,5 ]-3-decene derivative including such as those mentioned below.
  • Tricyclo[4.4,0,1 2,5 ]-3-undecene derivative including such as those mentioned below.
  • Pentacyclo[6,5,1,1 3,6 .0 2,7 .0 9,13 ]-4-pentadecene derivative including such as those mentioned below.
  • Diene compound including such as mentioned below.
  • Pentacyclo[7.4.0.1 2,5 .1 9,12 .0 8,13 ]-3-pentadecene derivative including such as those mentioned below.
  • Heptacyclo[8.7.0.1 3,6 .1 10,17 .1 12,15 .0 2,7 .0 11,16 ]-4-eicosene derivative including such as those mentioned below.
  • Nonacyclo[10.9.1.1 4,7 .1 13,20 .1 15,18 .0 3,8 .0 2,10 .0 12,21 . 0 14,19 ]-5-pentacosene derivative including such as those mentioned below.
  • cycloolefins of the above-mentioned formula [II] used in the present invention include concretely such compounds as shown below.
  • the cycloolefin random copolymer comprising ethylene units and the aforementioned cycloolefin units as essential component may contain, if necessary, in addition to these two essential component, other copolymerizable unsaturated monomer units within limits prejudicial to the object of the present invention.
  • Such copolymerizable unsaturated monomer units useful in the cycloolefin random copolymer may be derived from monomers including ⁇ -olefins of 3-20 carbon atoms such as propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosane, and these unsaturated monomers may be used, for example, in amounts less than equimolar amount of the ethylene units present in the resulting random copolymer.
  • monomers including ⁇ -olefins of 3-20 carbon atoms such as propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-o
  • a recurring unit (a) derived from ethylene is present in a proportion of 40-85 mol%, preferably 50-75 mol%
  • a recurring unit (b) derived from the cycloolefin is present in a proportion of 15-60 mol%, preferably 25-50 mol%
  • the recurring units (a) and (b) are arranged substantially linear at random.
  • the constitution in the resulting random copolymer of ethylene and cycloolefin was determined by 13 C-NMR. The fact that this random copolymer is substantially linear and has no gel-like crosslinked structure can be confirmed by the fact that the copolymer completely dissolves in decalin at 135°C.
  • the cycloolefin random copolymer [A] has an intrinsic viscosity [ ⁇ ], as measured in decalin at 135°C, of 0.05-10 dl/g, preferably 0.08-5 dl/g.
  • a softening temperature (TMA), as measured with a thermal mechanical analyzer, of the cycloolefin random copolymer [A] is at least 70°C, preferably 90-250°C and especially 100-200°C.
  • This softening temperature (TMA) was determined by the behavior on heat deformation of a sheet of a 1 mm thick of the cycloolefin random copolymer using Thermomechanical Analyser (manufactured by Du Pont). That is, a quartz needle is put vertically on the sheet under a load of 49 g, the sheet is then heated at a heating rate of 5°C/min, and the temperature at which the needle has intruded into the sheet to a depth of 0.635 mm is taken as TMA.
  • a glass transition temperature (Tg) of this cycloolefin random copolymer [A] is usually 50-230°C, preferably 70-210°C.
  • a crystallinity index, as measured by X ray diffractometry, of the cycloolefin random copolymer [A] is 0-10 %, preferably 0-7 %, especially 0-5 %.
  • the cycloolefin random copolymer [B] which is a copolymer of ethylene and cycloolefin represented by the aforementioned formula [I] or [II] having an intrinsic viscosity [ ⁇ ] of 0.01-5 dl/g and a softening temperature (TMA) of less than 70°C.
  • a recurring unit (a) derived from ethylene is present in a proportion of 60-98 mol%, preferably 60-95 mol%
  • a recurring unit (b) derived from the cycloolefin is present in a proportion of 2-40 mol%, preferably 5-40 mol%
  • the recurring units (a) and (b) are arranged substantially linear at random.
  • the constitution in the resulting random copolymer of ethylene and cycloolefin was determined by 13 C-NMR. The fact that this cycloolefin random copolymer [B] is substantially linear and has no gel-like crosslinked structure can be confirmed by the fact that the copolymer completely dissolves in decalin at 135°C.
  • the cycloolefin random copolymer [B] has an intrinsic viscosity [ ⁇ ], as measured in decalin at 135°C, of 0.01-5 dl/g, preferably 0.05-5 dl/g, more preferably 0.08-3 dl/g.
  • a softening temperature (TMA), as measured with a thermal mechanical analyzer, of the cycloolefin random copolymer [B] is less than 70°C, preferably -10-60°C and especially 10-55°C.
  • a glass transition temperature (Tg) of this cycloolefin random copolymer [B] is usually -30-60°C, preferably -20-50°C.
  • a crystallinity index, as measured by X-ray diffractometry, of the cycloolefin random copolymer [B] is 0-10%, preferably 0-7% and especially 0-5%.
  • the weight ratio in the composition of the cycloolefin random copolymer [A]/the cycloolefin random copolymer [B] is from 100/0.1 to 100/10, preferably 100/0.3 to 100/7 and especially from 100/0.5 to 100/5.
  • the substrate resulting therefrom has such an effect that adhesion between the substrate and the first protective film used in the present invention under severe conditions is further improved in comparison with the case of a substrate composed of the [A] component alone, while maintaining excellent transparency and surface smoothness inherent in the substrate.
  • the substrate of the present invention composed of the above-mentioned cycloolefin random copolymer composition containing a blend of the [A] and [B] components as defined above, excellent adhesion obtained between the substrate and the first protective film used in the invention has such characteristics that no undesirable changes in the adhesion thus obtained will occur even after allowing the substrate bearing the first protective film to stand under the circumstances of high temperature and humidity.
  • cycloolefin random copolymers [A] and [B] constituting the substrate of the invention may be prepared by suitably selecting the conditions under which these copolymers are prepared in accordance with the processes proposed by the present applicant in Japanese Patent L-O-P Publns. Nos. 168708/1985, 120816/1986, 115912/1986 and 115916/1986, Japanese Patent Applns. Nos. 95905/1986 and 95906/1986, and Japanese Patent L-O-P Publns. Nos. 271308/1986 and 272216/1986.
  • the resins constituting the substrate of the invention may include, in addition to the above-mentioned cycloolefin random copolymers, polymers or copolymers containing a recurring unit represented by the following formula [III] formed by ring opening polymerization of the aforementioned cycloolefin represented by the formula [I], and further include polymers or copolymers containing a recurring unit represented by the following formula [IV] formed by hydrogenation of the recurring unit represented by the formula [III].
  • R 1 -R 12 are as defined in the aforementioned formula [I].
  • cycloolefin random copolymers as illustrated above may be incorporated with various additives such as heat stabilizers, weathering stabilizers, antistatic agents, slip agents, anti-blocking agents, anti-fogging agents, lubricants, dyes, pigments, natural oil, synthetic oil and wax, and amounts of these additives used may be suitably decided.
  • additives such as heat stabilizers, weathering stabilizers, antistatic agents, slip agents, anti-blocking agents, anti-fogging agents, lubricants, dyes, pigments, natural oil, synthetic oil and wax, and amounts of these additives used may be suitably decided.
  • the stabilizers which may be used optionally include, in concrete, phenolic antioxidants such as tetrakis[methylene-3(3,5-di-t-butyl-4-hydroxyphenyl) propionate]methane, ⁇ -(3,5-di-t-butyl-hydroxyphenyl) propionic acid alkyl ester (particularly preferred are alkyl esters of not more than 18 carbon atoms) and 2,2'-oxamidebis[ethyl-3-(3,5-di-t-butyl-hydroxyphenyl)] propionate, fatty acid metal salts such as zinc stearate, calcium stearate and calcium 12-hydroxystearate, and fatty acid esters of polyhydric alcohol such as glycerin monostearate, glycerin monolaurate, glycerin distearate, pentaerythritol monostearate, pentaerythritol distearate and pentaerythri
  • stabilizers may be used singly, but may also be used in combination, for example, a combination use of tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane with zinc stearate and glycerin monostearate.
  • phenolic antioxidants in combination with fatty acid esters of polyhydric alcohol, said fatty acid esters being preferably those of polyhydric alcohol exhibiting at least three valences, in which part of the hydroxy groups has been esterified.
  • Such fatty acid esters of polyhydric alcohol as mentioned above include concretely fatty acid esters of glycerin such as glycerin monostearate, glycerin monolaurate, glycerin monomyristate, glycerin monopalmitate, glycerin distearate and glycerin dilaurate, and fatty acid esters of pentaerythritol such as pentaerythritol monostearate, pentaerythritol monolaurate, pentaerythritol distearate, pentaerythritol dilaurate and pentaerythritol tristearate.
  • glycerin such as glycerin monostearate, glycerin monolaurate, glycerin monomyristate, glycerin monopalmitate, glycerin distearate and glycerin dilaurate
  • the phenolic antioxidants as mentioned above are used in an amount, based on 100 parts by weight of the cycloolefin random copolymer composition, of 0.01-10 parts by weight, preferably 0.05-3 parts by weight and especially 0.1-1 part by weight, and the fatty acid esters of polyhydric alcohol are used in an amount, based on 100 parts by weight of the composition, of 0.01-10 parts by weight, preferably 0.05-3 parts by weight.
  • the substrate used is preferably composed of the cycloolefin random copolymer [A] or the composition containing said cycloolefin random copolymer [A] as aforesaid, and these media are superior in optical properties and in adhesion between said substrate and a first protective film formed thereon and accordingly the recording film is excellent in long-term stability and, at the same time, is effectively prevented from oxidation. Further the warp of substrate is rather small even when the substrate is kept in high humidity for a long period of time.
  • the magnetooptical recording media having the above-mentioned substrate are excellent in service durability, and they are free from cracking.
  • a thickness of the substrate is not limited particularly, the substrate 2 of the present invention as illustrated hereinbefore has preferably a thickness of 0.5-mm, more preferably 1-2 mm.
  • the first protective film 3 and the second protective film 5 used in the magnetooptical recording medium 1 of the present invention are films represented by the constitutional formula SiNx, for example, silicon nitride or silicon nitride-containing films.
  • Particularly useful protective films of the formula SiNx in which x is preferably 0 ⁇ x ⁇ 4/3 include concretely films of silicon nitride such as Si 3 N 4 (silicon tetranitride) or films of the formula SiNx containing a mixture of Si 3 N 4 and Si, in which x is 0 ⁇ x ⁇ 4/3.
  • Such protective films as represented by the formula SiNx may be formed by the sputtering method using Si 3 N 4 or Si 3 N 4 and Si as a target.
  • Such protective films may also be formed by the sputtering method using a Si target in a nitrogen atmosphere.
  • the first protective film 3 and the second protective film 5 represented by the formula SiNx desirably have a refractive index of usually at least 1.8 preferably 1.8-2.2, and these protective films play a role in preventing the magnetooptical recording film 4 mentioned later from oxidation or the like deterioration or function as an enhancing film to improve recording characteristics of said magnetooptical recording film 4.
  • These protective films represented by the formula SiNx (0 ⁇ x ⁇ 4/3) are also excellent particularly in crack resistance.
  • the magnetooptical recording media of the present invention are broad in recording power margin and are small in dependence on linear velocity, because the magnetooptical recording media have a four films laminated structure of the first protective film, a specific magnetooptical recording film, the second protective film and a metallic film composed of an aluminum alloy on the substrate, and the first protective film and the second protective film are composed of SiNx.
  • the magnetooptical recording medium comprising the first protective film of the above-mentioned film thickness has a large ⁇ k. Further the magnetooptical recording medium comprising the second protective film of the above-mentioned film thickness has broad recording power margin without deteriorating excellent C/N ratio.
  • the first protective film 3 of the invention has a film thickness of 500-2000 ⁇ , preferably 800-1500 ⁇ , and the second protective film 5 has a film thickness of 50-2000 ⁇ , preferably 50-1000 ⁇ and especially 100-700 ⁇ or thereabouts.
  • the magnetooptical recording film 4 comprises (i) at least one metal selected from 3d transition metals, and (iii) at least one element selected from among rare earth elements.
  • the magnetooptical recording film 4 comprises (i) at least one metal selected from 3d transition metals, (ii) at least one metal selected from corrosion-resistant metals, and (iii) at least one element selected from among rare earth elements.
  • 3d transition metals (i) are Fe, Co, Ti, V, Cr, Mn, Ni, Cu and Zn, and among these, preferred is Fe or Co, or both of them.
  • This 3d transition metal is contained in the magnetooptical recording film 4 in an amount of 20-90 atom%, preferably 30-85 atom% and especially 35-80 atom%.
  • Useful corrosion-resistant metals are Pt, Pd, Ti, Zr, Ta and Nb, and among these, preferred are Pt, Pd and Ti, and particularly preferred is Pt or Pd, or both of them.
  • the corrosion-resistant metal is present based on all atoms constituting the magnetooptical recording film in an amount of not more than 30 atom%, preferably 5-30 atom%, more preferably 5-25 atom%, especially 10-25 atom% and more specifically 10-20 atom%.
  • the change of the coercive force Hc of the magnetooptical recording film is small and the decrease of the Kerr rotation angle is also small after a long period of time.
  • the magnetooptical recording film 4 contains, in addition to the above-mentioned component (i), at least one rare earth element selected from the following group.
  • At least one element selected from the above-mentioned group is present in the magnetooptical recording film 4 in an amount of 5-50 atom%, preferably 8-45 atom% and especially 10-40 atom%.
  • the magnetooptical recording film 4 desirably have the following composition.
  • the magnetooptical recording films used in the present invention contain desirably Fe or Co, or both of them as the 3d transition metal (i), and the content of Fe and/or Co in the recording film is at least 40 atom% but not more than 80 atom%, preferably at least 40 atom% but less than atom% and especially at least 40 atom% but not more than 59 atom%.
  • Fe and/or Co is present desirably in such an amount that Co/(Fe+Co) ratio (atomic ratio) is at least 0 but not more than 0.3, preferably at least 0 but not more than 0.2 and especially at least 0.01 but not more than 0.2.
  • the amount of Fe and/or Co used in the magnetooptical recording film is in the range of at least 40 atom% but not more than 80 atom%, there are obtained such advantages that the resulting magnetooptical recording film is excellent in oxidation resistance and has a magnetic easy axis perpendicular to the film.
  • Co/(Fe+Co) ratio (atomic ratio) in the magnetooptical recording film is at least 0 but not more than 0.3, preferably at least 0 but not more than 0.2 and especially at least 0.01 but not more than 0.2.
  • the magnetooptical recording films used in the present invention as illustrated above will not be subject to change of properties even when they are used repeatedly in recording and erasing information.
  • the magnetooptical recording film of the present invention having the composition of Pt 13 Tb 28 Fe 50 Co 9 no decrease in C/N ratio is observed even when the recording and erasing of information are carried out repeatedly 100,000 times.
  • the magnetooptical recording films of the present invention contain, as the corrosion-resistant metal, (ii) Pt or Pd, or both of them, and Pt and/or Pd is desirably present in the magnetooptical recording film in an amount of 5-30 atom%, preferably exceeding 10 atom% but not more than 30 atom%, especially exceeding 10 atom% but less than atom% and most suitably at least 11 atom% but not more than 19 atom%.
  • the amount of Pt and/or Pd contained in the magnetooptical recording film is at least 5 atom%, especially in excess of 10 atom%, there are obtained such advantages that the resulting recording film is excellent in oxidation resistance, wherein no corrosion occurs even when the recording film is used for a long period of time and no deteriorative change in C/N ratio is observed.
  • the magnetooptical recording film of the present invention having the composition of Pt 13 Tb 28 Fe 50 Co 9 (atom%) or Pd 12 Tb 28 Fe 57 Co 3 (atom%), no change in C/N ratio is observed at all even when the recording film is held for 1000 hours under the circumstances of 85% RH and 80°C.
  • a sufficiently high C/N ratio is obtained with a small bias magnetic field applied. If a sufficiently high C/N ratio is obtained with a small bias magnetic field, a simplified driving device can be used for driving an optical disc having a magnetooptical recording film, because a magnet for generating bias magnetic field can be minimized in size and, moreover, development of heat from the magnet can be reduced to the fullest extent. Since a sufficiently high C/N ratio is obtained, it becomes easy to design a magnet for magnetic field modulation recording capable of overlight.
  • a rare earth element (RE) is contained, and the rare earth element used includes Nd, Sm, Pr, Ce, Eu, Gd, Tb, Dy or Ho.
  • rare earth elements as exemplified above, preferably used are Nd, Pr, Gd, Tb and Dy, and particularly preferred is Tb. These rare earth elements may be used in a combination of two or more elements, and in this case the content of Tb out of the elements used is desirably at least 50 atom%.
  • the rare earth elements are present in the magnetooptical recording film in such an amount that RE/(RE+Fe+Co) ratio (atomic ratio) represented by x is 0.15 ⁇ x ⁇ 0.45, preferably 0.20 ⁇ x ⁇ 0.4.
  • the amounts of these elements contained in the magnetooptical recording film is not more than 10 atom% based on all atoms constituting the recording film.
  • (I) 3d transition elements other than Fe and Co for example, including concretely Sc, Ti, V, Cr, Mn, Ni, Cu and Zn.
  • (II) 4d transition elements other than Pd for example, including concretely Y, Zr, Nb, Mo, Tc, Ru, Rh, Ag and Cd.
  • (III) 5d transition elements other than Pt for example, including concretely Hf, Ta, W, Re, Os, Ir, Au and Hg.
  • Useful elements are concretely B, Al, Ga, In and Tl.
  • Useful elements are concretely C, Si, Ge, Sn and Pb.
  • Useful elements are concretely N, P, As, Sb and Bi.
  • Useful elements are concretely S, Se, Te and Po.
  • Te preferably used is Te.
  • magnetooptical recording films composed of (i) at least one member selected from 3d transition metals and (iii) at least one element selected from rare earth elements mentioned above can also be used.
  • Such magnetooptical recording films are preferably those of TbFeCo series, wherein preferably the amount of Tb is from 10 to 40 atom%, that of Fe is from 30 to 90 atom% and that of Co is from 0 to 30 atom%.
  • magnetooptical recording films, containing (i) a 3d transition metal and (iii) a rare earth element as mentioned above, may further contain other elements (e.g. elements of (I) - (VII) mentioned above).
  • the magnetooptical recording film 4 having the composition as defined above is an amorphous film which has a magnetic easy axis perpendicular to the film, Kerr hysteresis loop of which exhibits in most cases favorable square shape, and which is capable of vertical magnetic and magnetooptical recording.
  • the expression used to the effect that Kerr hysteresis loop exhibits favorable square shape is intended to mean the fact that a ratio ⁇ k 2 / ⁇ k 1 of the Kerr rotation angle at a saturation magnetization ( ⁇ k 1 ) in the maximum external magnetic field to the Kerr rotation angle at a remnant magnetization ( ⁇ k 2 ) in the magnetic field of zero is more than 0.8.
  • This magnetooptical recording film 4 has a film thickness of 100-600 ⁇ , preferably 100-400 ⁇ and especially 150-350 ⁇ or thereabouts.
  • a metallic film 6 is provided on the aforementioned second protective film 5.
  • the metallic film 6 used in the invention is composed of an aluminum alloy.
  • This aluminum alloy contains aluminum and at least one element other than aluminum.
  • the aluminum alloys as exemplified above those mentioned below are particularly preferred, because they are excellent in corrosion resistance. And the magnetooptical recording media having the metallic film composed of the aluminum alloys are small in dependence on linear velocity.
  • the magnetooptical recording film is that of (i) at least one metal selected from 3d transition metals, and (iii) at least one element selected from among rare earth elements
  • the metallic film composed of the above-mentioned particularly preferred aluminum alloys is used.
  • the metallic film 6 as illustrated above may be deposited on the second protective film, for example, by the sputtering method or the like using a composite target of the above-mentioned elements or an alloy target containing said elements.
  • the above-mentioned metallic film may contains one or two or more metals (elements) in addition to metals constituting the metallic film 6.
  • metals as referred to above may include, for example, titanium (Ti), hafnium (Hf), niobium (Nb) chromium (Cr), silicon (Si), tantalum (Ta), copper (Cu), tungsten (W), zirconium (Zr), manganese (Mn), magnesium (Mg) and vanadium (V), and the amount of these metals to be contained is usually not more than 5 atom%, preferably not more than 2 atom%.
  • any metals (elements) out of those exemplified above are contained, even when their amount is in the range as defined above, in the metallic film 6 if said metals (elements) have already been present in the metallic film 6).
  • the aluminum alloy constituting the metallic film 6 is Al-Ti alloy or Al-Ti-Hf alloy, no titanium (Ti) out of the above-exemplified metals (elements) is contained in this aluminum alloy.
  • the metallic film 6 used in the present invention desirably has a film thickness of 100-5000 ⁇ , preferably 500-3000 ⁇ and especially 700-2000 ⁇ .
  • the metallic film used in the present invention functions as a good heat conductor layer, and by the presence of this metallic film in the magnetooptical recording medium, the center portion of pits recorded in the recording film is prevented from excessive heating by the recording beam applied thereto and, as the result it is considered that dependence on linear velocity of the recording power used is made small.
  • an overcoat layer may be provided on the metal film.
  • An UV-ray polymerization resin for example, an acryl type UV-ray polymerization resin is preferably used as an overcoating agent, and the resultant coating has preferably a thichness of 1-100 ⁇ m.
  • the substrate may also be coated with a top coat on the side opposite to the protective film.
  • the double-sided magnetooptical recording media of the present invention are illustrated hereinafter.
  • the double-sided magnetooptical recording medium 20 of the invention has such a structure that a first magnetooptical recording medium having laminated first protective film (11a), a magnetooptical recording film (12a), a second protective film (13a) and a metallic film (14a) on a substrate (10a) in that order and a second magnetooptical recording medium having laminated a first protective film (11b), a magnetooptical recording film (12a), a second protective film (13b) and a metallic film (14b) on a substrate (10b) in that order are joined together with an adhesive layer 15 interposed between the two recording films so that the metallic film (14a) of the first magnetooptical recording medium and the metallic film (14b) of the second magnetooptical recording medium are faced with each other.
  • the metallic film (14a) and/or the metallic film (14b) may also be coated with the overcoat to improve long-time reliance of the magnetooptical recording medium, and in this case the first magnetooptical recording medium and the second magnetooptical recording medium are joined together with the adhesive layer 15 so that the overcoats are faced with each other.
  • the substrates 10a and 10b, the first protective films 11a and 11b, the magnetooptical recording films 12a and 12b, the second protective films 13a and 13b and the metallic films 14a and 14b used in the above-mentioned double sided magnetooptical recording medium are the same as those illustrated hereinbefore.
  • the metallic film 14a of the first magnetooptical recording medium and the metallic film 14b are joined together with the adhesive layer 15.
  • the adhesive layer 15 may be formed from hot-melt adhesives such as polyolefin, EVA, synthetic rubber, polyester and polyamide, or reactive adhesives such as resorcinol, cyanoacrylate, epoxy, urethane and ultraviolet curing acrylate. In the present invention, however, preferably useful are hot-melt adhesive.
  • hot-melt adhesives as illustrated above, preferably useful in the invention are polyolefin hot-melt adhesives having a softening point of at least 130°C, preferably that exceeding 140°C and especially that of at least 141°C.
  • hot-melt adhesives having a softening point of at least 130°C are polyolefin hot-melt adhesives containing polyolefins (A), styrene resins (B) and tackifiers (C).
  • the polyolefins (A) used include ethylene/propylene/ ⁇ -olefin random terpolymers, ethylene/propylene random copolymer and polyisobutylene.
  • the ⁇ -olefin constituting the above-mentioned random terpolymer includes C 4 -C 20 ⁇ -olefins, particularly preferred are 1-butene and 4-methyl-1-pentene.
  • the styrene resins (B) used include polymers or copolymers containing styrene or styrene derivatives as the constituent thereof, such as polystyrene, styrene/ ⁇ -methylstyrene copolymers and stylene/ ⁇ -methylstyrene/vinyl toluene copolymers. Of these styrene resins, particularly preferred is polystyrene.
  • the tackifiers (C) used include such petroleum resins as aromatic petroleum resins (e.g. C 9 petroleum resin), aliphatic petroleum resins (C 5 petroleum resin), aromaticaliphatic copolymer petroleum resins (C 9 -C 5 copolymer resin) and aliphatic cyclic resins.
  • aromatic petroleum resins e.g. C 9 petroleum resin
  • C 5 petroleum resin aliphatic petroleum resins
  • aromaticaliphatic copolymer petroleum resins C 9 -C 5 copolymer resin
  • aliphatic cyclic resins desirably used are petroleum resins having a number average molecular weight of not more than 3000, particularly, 500-3000, and a softening point of 80-150°C.
  • aliphatic cyclic resins having a weight average molecular weight of not more than 5000 preferably 50-3000.
  • the proportion of the constituent (A) is 1-60% by weight, preferably 5-40% by weight, that of the constituent (B) is 1-30% by weight, preferably 5-20% by weight, and that of the constituent (C) is 30-95% by weight, preferably 50-90% by weight.
  • the double-sided magnetooptical recording media are also excellent in oxidation resistance, free from derterioration of magnetooptical recording characteristics even when used for an extended period of time, high in C/N ratio, broad in recording power margin and small in dependence on livear velocity of recording sensitivity.
  • the double-sided magnetooptical recording medium are free from warps.
  • the first protective film, magnetooptical recording film, second protective film and metallic film as illustrated hereinbefore may be deposited respectively on the substrate by the known method such as sputtering, electron beam deposition, vacuum deposition or ion plating.
  • the magnetooptical recording media of the present invention are excellent in oxidation resistance, free from deterioration of magnetooptical recording characteristics even when used for an extended period of time, high in C/N ratio, broad in recording power margin an small in dependence on linear velocity of recording sensitivity.
  • the magnetooptical recording media of the invention are broad in recording power margin, because the magnetooptical recording media have specific four films laminated structure [namely a structure of substrate/a first protective film (SiNx)/a specific recording layer/a second protective film (SiNx)/an aluminum alloy film] and have a metallic film composed of the aluminum alloy film.
  • the magnetooptical recording media are small in dependence on linear velocity of recording sensitivity, because the magnetooptical recording media have the metallic film composed of an aluminum alloy.
  • the substrate composed of the specific cycloolefin random copolymer as aforementioned is used, an increase in adhesion between the substrate and the first protective film can be obtained.
  • the double-sided magnetooptical recording media have the excellent properties as listed above and are excellent in mechanical properties such as free from warps.
  • optimum recording power designates a recording power with which writing signals at a frequency of 1 MHz and a duty factor of 50% are recorded and which makes minimum the secondary harmonics of signals reproduced from the recorded signals. Recording media show a lower degree of dependence on the linear velocity when the information recording media show smaller difference of the optimum recording powers determined at different linear velocities.
  • a substrate having a thickness of 1.2 mm
  • an amorphous polyolefin obtained by copolymerizing ethylene and 1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene (structural formula: hereinafter called DMON for short)
  • DMON structural formula: hereinafter called amorphous polyolefin
  • TMA softening temperature
  • Si 3 N 4 film was then deposited an aluminum alloy film composed of Al 96 Cr 2 Hf 2 represented in terms of atom% as a metallic film to a thickness of 1800 ⁇ by the sputtering method using a composite target composed of Al-Cr-Hf.
  • Characteristics of the magnetooptical recording medium thus obtained were determined in the following manner.
  • the adhesion was evaluated by subjecting the thus treated specimen to peeling test using a scotch tape in the usual way.
  • Example 1 was repeated except that the Si 3 N 4 film used as the second protective film had a film thickness of 240 ⁇ .
  • Example 2 On the same substrate as used in Example 1 was deposited a Si 3 N 4 film as a first protective film by the sputtering method to a thickness of 1000 ⁇ using a Si 3 N 4 target.
  • Example 3 was repeated except that the Si 3 N 4 film used as the second protective film had a film thickness of 350 ⁇ .
  • Example 2 On the same substrate as used in Example 1 was deposited a Si 3 N 4 film as a first protective film to a film thickness of 1100 ⁇ by the sputtering method using a Si 3 N 4 target.
  • Example 5 was repeated except that the Si 3 N 4 film used as the second protective film had a film thickness of 120 ⁇ .
  • Example 2 On the same substrate as used in Example 1 was deposited a Si 3 N 4 film as a first protective film to a film thickness of 1100 ⁇ by the sputtering method using a Si 3 N 4 target.
  • Example 7 was repeated except that the Si 3 N 4 film used as the second protective film had a film thickness of 320 ⁇ .
  • 100/100 means that, among 100 pieces, 100 pieces remain after the peeling test.
  • the (A)/(B) blend thus obtained was incorporated with, as stabilizers, tetrakis methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl propionate methane, zinc stearate and glycerin monostearate in amounts, based on the sum total of the resins (A) and (B), of 0.5% by weight, 0.05% by weight and 0.5% by weight, respectively.
  • Example 9 was repeated except that the Si 3 N 4 film used as the second protective film had a film thickness of 240 ⁇ .
  • the magnetooptical recording medium thus obtained was evaluated in the same manner as in Example 9.
  • Example 9 On the same substrate as used in Example 9 was deposited a Si 3 N 4 film as a first protective film to a film thickness of 1000 ⁇ by the sputtering method using a Si 3 N 4 target.
  • Adhesion between the substrate and the enhancing film of the thus obtained magnetooptical recording medium was evaluated in the same manner as in Example 9.
  • Example 11 was repeated except that the Si 3 N 4 film used as the second protective film had a film thickness of 350 ⁇ .
  • Example 9 On the same substrate as used in Example 9 was deposited a Si 3 N 4 film as a first protective film to a film thickness of 1100 ⁇ by the sputtering method using a Si 3 N 4 target.
  • Adhesion between the substrate and the enhancing film of the magnetooptical recording medium thus obtained was evaluated in the same manner as in Example 9.
  • Example 13 was repeated except that the Si 3 N 4 film used as the second protective film had a film thickness of 120 ⁇ .
  • Example 9 On the same substrate as used in Example 9 was deposited a Si 3 N 4 film as a first protective film to a film thickness of 1100 ⁇ by the sputtering method using a Si 3 N 4 target.
  • Adhesion between the substrate and the enhancing film of the magnetooptical recording medium was evaluated in the same manner as in Example 9.
  • Example 15 was repeated except that the Si 3 N 4 film used as the second protective film had a film thickness of 320 ⁇ .
  • Example 2 On the same substrate as used in Example 1 were consecutively deposited, by sputtering, a Si 3 N 4 film as a first protective film having a thickness of 1000 ⁇ , a Pt 9 Tb 29 Fe 58 Co 4 (atom%) film as a magnetooptical recording film having a thickness of 270 ⁇ , a Si 3 N 4 film as a second protective film having a thickness of 160 ⁇ and an Al 96 Cr 2 Hf 2 (atom%) film as a metallic film having a thickness of 1800 ⁇ to obtain a megnetooptical recording medium.
  • the metallic films of two of these magnetooptical recording medium were coated, by a roll coater, with a hot melt adhesive (composition: 21% by weight of an ethylene/propylene/1-butene ternary copolymer, 10% by weight of a polystyrene having a Tg of 110°C and MFR of 25 g/10 min, and 69% by weight of a petroleum resin having a number average molecular weight of 1500) having a softening temperature of 145°C.
  • a hot melt adhesive composition: 21% by weight of an ethylene/propylene/1-butene ternary copolymer, 10% by weight of a polystyrene having a Tg of 110°C and MFR of 25 g/10 min, and 69% by weight of a petroleum resin having a number average molecular weight of 1500
  • Two of the magnetoopotical recording medium thinly coated with the hot melt adhesive were placed in such a manner that both metallic layers of the two medium faced each other, and bonded together by a cold pressing machine to obtain a double-sided recording type magnetooptical recording medium.
  • Example 17 was repeated except that the composition of the magnetooptical recording film and the metallic film and/or the thickness of the constituent films were altered as described in Table 5 to obtain a double-sided recording type magnetooptical recording medium.
  • the recording medium was tested, and results obtained are shown in Table 5.
  • the composition of the magnetooptical recording films and the metallic films is represented in terms of atom%.
  • Example 1 was repeated except that the composition of the protective films, magnetooptical recording film and/or metallic film, and the thickness of the constituent films were altered as described in Table 6, and that a polycarbonate substrate was used in Example 28 in place of the ethylene/DMON copolymer substrate to obtain single-sided magnetooptical recording media.
  • the recording media were tested, and results obtained were shown in Table 6.
  • the composition of the protective films is represented in terms of an atomic ratio, and that of the magnetooptical recording films and metallic films is represented in terms of atom%.
  • the refractive index of the protective film used in Example 26 was 2.1 and that of the protective film used in Example 27 was 1.9.
  • the metallic film of a magnetooptical recording medium obtained by repeating Example 5 was coated, by a roll coater, with an acrylic UV-ray polymerization resin (trade name of SD101, from Dainippon Ink Corporation) to form an overcoat having a thickness of 10 ⁇ m.
  • an acrylic UV-ray polymerization resin (trade name of SD101, from Dainippon Ink Corporation)
  • the obtained magnetooptical recording medium was tested by a procedure similar to that in Example 1.
  • a Byte Error Rate (BER) was determined after 20 cycles of a heat cycle test in which the recording medium was left in an atmosphere changing its temperature from 65°C to -40°C in 24 hours (1 cycle).
  • the recording medium showed an optimum recording power of 4.8 mW at a linear velocity of 5.7 m/sec and 6.4 mW at a linear velocity of 11.3 m/sec, respectively, a power margin of 5.1 mW, a C/N ratio of 48 dB, and a BER of 1x10 -5 initially and 1x10 -5 after the 20 cycles of the heat cycle test.
  • the metallic film of a magnetooptical recording medium obtained by repeating Example 5 was coated, by a roll coater, with an acrylic UV-ray polymerization resin (trade name of SD101, from Dainippon Ink Corporation) to form an overcoat having a thickness of about 1.0 ⁇ m.
  • an acrylic UV-ray polymerization resin trade name of SD101, from Dainippon Ink Corporation
  • Two of the magnetooptical recording media were bonded together with some adhesive and by the same procedure as used in Example 17 to obtain a double-sided recording type magnetooptical recording medium.
  • the obtained recording medium showed an optimum recording power of 4.9 mW at a linear velocity of 5.7 m/sec and 6.5 mW at a linear velocity of 11.3 m/sec, respectively, a power margin of 5.5 mW, a C/N ratio of 48 dB, a ⁇ C/N ratio of 0, no warp, and a BER of 1x10 -5 initially and 1x10 -5 after 20 cycles of the heat cycle test described in Example 31.
  • Example 1 was repeated except that a magnetooptical recording film composed of Tb 30 Fe 66 Co 4 was used in place of the magnetooptical recording film composed of Pt 9 Tb 29 Fe 58 Co 4 , the compositon of both films being represented in terms of atom%.
  • the obtained magnetooptical recording medium was tested, and the same optimum recording power, power margin and adhesion values as Example 1 were obtained, and a C/N ratio of 49 and a ⁇ C/N ratio of -6 were obtained.
  • Example 21 was repeated except that a magnetooptical recording film composed of Tb 30 Fe 66 Co 4 was used in place of the magnetooptical recording film composed of Pt 10 Tb 30 Fe 58 Co 2 , the composition of both films being represented in terms of atom%.
  • the obtained magnetooptical recording medium was tested, and the same optimum recording power, power margin and adhesion values as Example 1 were obtained, and a C/N ratio of 48.5 and a ⁇ C/N ratio of -5 were obtained.

Claims (13)

  1. Support d'enregistrement magnétooptique ayant, sur un substrat, un premier film de protection, un film d'enregistrement magnétooptique, un second film de protection et un film métallique dans cet ordre, dans lequel :
    les premier et second films de protection sont constitués chacun de SiNx où x est 0 < x ≤ 4/3; et
    le film d'enregistrement magnétooptique est constitué d'un film d'alliage amorphe qui a un axe d'aimantation aisée perpendiculaire au film et comprend (i) au moins un métal choisi parmi les métaux de transition 3d, (ii) au moins un métal choisi parmi les métaux résistant à la corrosion et (iii) au moins un élément choisi parmi les éléments des terres rares, la teneur dudit métal résistant à la corrosion étant 5-30 atomes % par rapport à tous les atomes constituant le film d'enregistrement,
       caractérisé en ce que le film métallique est constitué d'un alliage d'aluminium.
  2. Support d'enregistrement magnétooptique ayant, sur un substrat, un premier film de protection, un film d'enregistrement magnétooptique, un second film de protection et un film métallique dans cet ordre, dans lequel :
    les premier et second films de protection sont constitués chacun de SiNx où x est 0 < x ≤ 4/3; et
    le film d'enregistrement magnétooptique est constitué d'un film d'alliage amorphe qui a un axe d'aimantation aisée perpendiculaire au film et comprend (i) au moins un métal choisi parmi les métaux de transition 3d, et (ii) au moins un élément choisi parmi les éléments des terres rares, caractérisé en ce que :
    le film métallique est composé d'un alliage d'aluminium.
  3. Support d'enregistrement magnétooptique à double face, dans lequel un premier support d'enregistrement magnétooptique ayant, sur un substrat, le premier film de protection, le film d'enregistrement magnétooptique, le second film de protection et le film métallique tels que décrits en revendication 1 dans cet ordre et un second support d'enregistrement magnétooptique ayant, sur un substrat, le premier film de protection, le film d'enregistrement magnétooptique, le second film de protection et le film métallique tels que décrits en revendication 1 dans cet ordre sont réunis par l'intermédiaire d'une couche adhésive de sorte que le film métallique du premier support d'enregistrement magnétooptique et le film métallique du second support d'enregistrement magnétooptique sont en regard l'un de l'autre.
  4. Support d'enregistrement magnétooptique selon la revendication 1, 2 ou 3, dans lequel le premier film de protection a une épaisseur de 400-2000 Å et le second film de protection a une épaisseur de 400-1000 Å.
  5. Support d'enregistrement magnétooptique selon la revendication 1 ou 3, dans lequel le film d'enregistrement magnétooptique est constitué de 20-90 atomes % d'un métal de transition 3d, de 5-30 atomes % d'un métal résistant à la corrosion et de 5-50 atomes % d'un élément des terres rares.
  6. Support d'enregistrement magnétooptique selon la revendication 1 ou 3, dans lequel le métal résistant à la corrosion est Pt et/ou Pd.
  7. Support d'enregistrement magnétooptique selon la revendication 1, 2 ou 3, dans lequel le film d'enregistrement magnétooptique a une épaisseur de 100-600 Å.
  8. Support d'enregistrement magnétooptique selon la revendication 1, 2 ou 3, dans lequel le film métallique a une épaisseur de 100-5000 Å.
  9. Support d'enregistrement magnétooptique selon la revendication 1, 2 ou 3, dans lequel le substrat est constitué d'un copolymère statistique de cyclooléfine ayant une viscosité intrinsèque (η) de 0,5-10 dl/g mesurée .dans la décaline à 135°C, ledit copolymère statistique étant un copolymère d'éthylène et d'au moins une cyclooléfine représentée par les formules [I] ou [II] suivantes :
    Figure imgb0105
     dans laquelle n est 0 (zéro) ou 1, m est 0 (zéro) ou un nombre entier positif, R1 - R18 sont individuellement un atome d'hydrogène, un atome d'halogène ou un groupe hydrocarbure, R15 - R18 peuvent, étant liés ensemble, former un cycle mono- ou polycyclique qui peut avoir une liaison double, et R15 avec R16 ou R17 avec R18 peut former un groupe alkylidène.
    Figure imgb0106
     dans laquelle 1 est 0 (zéro) ou un nombre entier d'au moins 1, m et n sont chacun 0 (zéro), 1 ou 2, R1-R15 sont individuellement un atome ou un groupe choisi dans le groupe constitué de l'hydrogène, d'un halogène, d'un hydrocarbure aliphatique, d'un hydrocarbure aromatique et d'un groupe alcoxy, et R5 (ou R6) et R9 (ou R7) peuvent être liés par l'intermédiaire d'un groupe alkylène ayant 1 à 3 atomes de carbone ou peuvent être liés directement sans passer par l'intermédiaire d'un groupe quelconque.
  10. Support d'enregistrement magnétooptique selon la revendication 9, dans lequel le substrat est constitué d'un copolymère statistique de cyclooléfine [A] ayant une viscosité intrinsèque [η], mesurée dans la décaline à 135°C, de 0,05-10 dl/g et une température de ramolissement (TMA) d'au moins 70°C.
  11. Support d'enregistrement magnétooptique selon la revendication 1, 2 ou 3, dans lequel le substrat est constitué d'un copolymère statistique de cyclooléfine [A] tel que défini en revendication 10, et d'un copolymère statistique de cyclooléfine [B] ayant une viscosité intrinsèque [η], mesurée dans la décaline à 135°C, de 0,05-5 dl/g et une température de ramollissement (TMA) de moins que 70°C, ledit copolymère statistique étant un copolymère de (a) éthylène et (b) au moins une cyclooléfine choisie dans le groupe constitué des monomères insaturés représentés par la formule [I] ou [II] décrite en revendication 9.
  12. Support d'enregistrement magnétooptique à double face selon la revendication 3, dans lequel le premier support d'enregistrement magnétooptique et/ou le second support d'enregistrement magnétooptique comportent en outre un revêtement sur la couche métallique.
  13. Support d'enregistrement magnétooptique selon la revendication 1, dans lequel le support d'enregistrement magnétooptique comporte en outre un revêtement sur la couche métallique.
EP90112759A 1989-07-05 1990-07-04 Milieux d'enregistrement magnéto-optique Expired - Lifetime EP0406823B1 (fr)

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JP173793/89 1989-07-05
JP17379389 1989-07-05
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JP16876590 1990-06-27

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EP0406823A3 EP0406823A3 (en) 1992-10-07
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EP0331737A1 (fr) * 1987-08-08 1989-09-13 Mitsui Petrochemical Industries, Ltd. Support d'enregistrement photomagnetique

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1303739C (fr) * 1987-06-02 1992-06-16 Fred W. Spong Enregistrements magneto-optiques
CA1309770C (fr) * 1987-12-10 1992-11-03 Hirokazu Kajiura Support d'enregistrement magneto-optique
KR920007319B1 (ko) * 1988-10-17 1992-08-29 미쓰이 세끼유 가가꾸 고오교오 가부시끼가이샤 광자기 기록매체
MY104246A (en) * 1988-10-20 1994-02-28 Mitsui Chemicals Inc Magnetooptical recording media.

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0331737A1 (fr) * 1987-08-08 1989-09-13 Mitsui Petrochemical Industries, Ltd. Support d'enregistrement photomagnetique

Also Published As

Publication number Publication date
EP0406823A3 (en) 1992-10-07
PL285931A1 (en) 1991-03-11
ATE159607T1 (de) 1997-11-15
EP0406823A2 (fr) 1991-01-09
DE69031612D1 (de) 1997-11-27
DE69031612T2 (de) 1998-03-12
CS335190A3 (en) 1992-11-18
CN1048944A (zh) 1991-01-30

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